Obstructive Sleep Apnea (OSA) refers to a sleep disorder usually caused by an obstruction or partial obstruction of the upper airway and a restriction of the air passage into the lungs. It is characterized by repetitive pauses in breathing or instances of shallow and infrequent breathing during sleep and it is usually associated with a reduction in blood oxygen saturation. Such pauses in breathing, called apneas, typically last 20 to 40 seconds. Less severe but also often causing a decreased amount of air movement into the lungs and a drop in oxygen level in the blood are episodes of overly shallow breathing or an abnormally low respiratory rate, called hypopnea. The obstruction of the upper airway is usually caused by reduced muscle tonus of the body that occurs during sleep. The human airway is composed of walls of soft tissue which can collapse and thereby obstruct breathing during sleep. Tongue tissue moves towards the back of the throat during sleep and thereby blocks the air passages. OSA is therefore commonly accompanied by snoring.
Different invasive and non-invasive treatments for OSA are known. One of the most powerful non-invasive treatments is the usage of continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP) in which the patient uses a machine (CPAP machine or BiPAP machine) that blows cleaned air, oxygen or any modification thereof in a pressurized or unpressurized way through the airway of the patient in order to keep it open.
One effect of OSA and also of the treatment with positive airway pressure (PAP) machines is that the patient's quality of sleep can be negatively affected and the patient may feel less rested in the morning. OSA patients may therefore run at risk to make mistakes due to drowsiness during the day. Such mistakes may especially be dangerous if a drowsy person operates a machine, e.g. a car.
A possible approach to cope with this is the concept of in-vehicle medical monitoring. In Kerr et al., “Driving with Diabetes in the Future: In-Vehicle Medical Monitoring”, Journal of Diabetes Science and Technology, Volume 4, Issue 2, March 2010, a study on diabetes patients is presented. The authors argue that driving a vehicle requires complex coordination of cognitive, motor, and sensory skills. These aspects can be affected adversely by diabetes per se, with hypoglycemia being the main concern for people with diabetes who drive. The authors present a concept of using the motor vehicle as a device to collect and deliver physiological and clinical information, which, in turn, may enable more people to drive more safely by reducing the chances of medical mishaps behind the wheel. This is particularly relevant for people living with diabetes who are at risk from a number of medical conditions that have the potential to have an impact on safe driving. The development of in-vehicle medical monitoring presents a new opportunity for novel collaborations between two industries, which have safety as a core value.
Further, in US 2013/0158423 A1, a mobile wellness device is disclosed. There is presented a system for acquiring electrical footprint of the heart, electrocardiogram (ECG) and heart rate variability monitoring, incorporated into a mobile device accessory. The ECG signal is conveniently acquired and transmitted to a server via the mobile device, offering accurate heart rate variability biofeedback measurement which is portable and comfortable during normal daily life. The presented system is claimed to provide a reliable tool for applications such as wellness, meditation, relaxation, sports and fitness training, and stress-relief therapy where accurate heart rate variability measurement is desired.
However, in spite the efforts on in-vehicle monitoring or mobile monitoring devices, the problem remains that it may be dangerous for OSA patients and bystanders if the OSA patient suffers from drowsiness during driving a car or operating another machine.
US 2009/0005652 A1 discloses methods and systems for controlling a subject's access to an activity based on a sleep quality index. The sleep quality index may include various physiological data relating to the subject, including current and historical physiological data, previous sleep quality indices for the subject. The subject's access to the activity may also be restricted based on personal characteristics of the subjects or on the identity of the subject.